<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // 1.条件语句
        let num=11
        if(num>=20){
            console.log('数字大于20')
        }
        else{
            console.log('数字小于20')
        }
        let shuzi=15
        if(shuzi<10){
            console.log('数字小于10')
        }
        if(shuzi>10&&shuzi<20){
            console.log('数字大于10小于20')
        }
        else{
            console.log('生成1')
        }
    </script>
</body>
</html>